High temperature, high pressure hydrocarbon conversion process

ABSTRACT

Hydroprocessing is effected by contacting the hydrocarbon with hydrogen in a low pressure, vapor-liquid contacting zone maintained under conditions sufficient to dissolve at least a portion of the hydrogen, with the resultant hydrocarbon liquid containing dissolved hydrogen being passed to a high temperature, high pressure reaction zone.

ilnite States Patent 1 Hallman 1 Jan. 30, 1973 [54] HIGH TEMPERATURE,HIGH 3,147,206 9/1964 Tulleners ..208/l ll X 2,985,582 5/1961 Oettinger..208/85 CONVERSION PROCESS Primary ExaminerDaniel E. Wyman [75]Inventor: Newt M. Hallman, Mt. Prospect, Ill. Assismm Examiner- P FShaver [73] Assignee: Universal Oil Products Company, gummy-JamesHoatson and Edward emus Des Plames, Ill. 22 Filed: Nov. 23, 1970 [57]ABSTRACT 2 A N 91,970 Hydroprocessing is effected by contacting thehydrocarbon with hydrogen in a low pressure, vapor liquid contactingzone maintained under conditions [52] US. Cl ..208/l1l, 208/85Sufficient to dissolve at least a portion of the Int. hydrogen resultanthydrocarbon con- [58] Field of Search ..208/l l l, 85 taining dissolvedhydrogen being passed to a high temperature, high pressure reactionzone. [56] References Cited V 8 Claims, I Drawlng Figure UNITED STATESPATENTS 3,l32,089 5/l964 Hass et al. 208/1 ll X fHydrogen HydrocarbonFeed 'Heater Separator Liquid 7'0 Fractionation HIGH TEMPERATURE, HIGHPRESSURE IIYDROCARBON CONVERSION PROCESS BACKGROUND OF THE INVENTION Theprocess of the present invention relates to the conversion ofhydrocarbons in the presence of hydrogen at high temperatures and highpressures. More specifically, the process of the present inventionrelates to the high temperature, high pressure hydrocracking ofpetroleum distillates or residual oils with decreased hydrogencompression costs.

Hydrocracking, wherein high molecular weight hydrocarbons are convertedto lower boiling saturate products, is extensively utilized in thepetroleum refining industry. As is well known to those people possessingexpertise in this art, hydrocracking requires the presence ofconsiderable amounts of hydrogen at high reaction temperatures andpressures. In these prior arts, a very significant portion of theoverall operatingv costs lies in the compression costs necessary toraise the pressureof the hydrogen to the levels necessary in the processsince. the hydrogen is typically available only from relatively lowpressure sources such as catalytic reformers.

SUMMARY or THE INVENTION It is the object of the present invention toprovide a more effective. high temperature,- high pressure hydrocarbonconversion process and, in particular, to provide a high temperature,high pressure hydrocracking process possessing lowerhydrogen compressioncosts than that obtainable in the present. art

processes.

These objects are accomplished by utilizingthe observation that hydrogenis more soluble in liquid hydrocarbons at elevated temperatures and thatit is, in general, more economical to pump liquids to a given pressurethan to compress gases to the same pressure.

In an embodiment, the present invention relates to an improvement in aprocess wherein a liquid hydrocarbon is contacted with hydrogen in ahigh pressure, high temperature reaction zone wherein the hydrocarbonand hydrogen are initially at a relatively low pressure, and areseparately raised to the high pressure of the reaction zone. Theparticular improvement resides in first contacting the hydrocarbon withhydrogen in a low pressure,;vapor-liquid contacting zone which ismaintained under conditions sufficient to dissolve at least a portion ofthe hydrogen in the liquid hydrocarbon so as to produce ahydrocarbonliquid containing dissolved hydrogen. This hydrogencontaining liquid is then passed to the high temperature, high pressurereaction zone. v

. In a further embodiment, the process of the present invention relatesto a method for hydroprocessing a liquidfhydrocarbon at an elevatedtemperature and pressure by first contacting the hydrocarbon and lowpressure hydrogen in a low pressure, vapor-liquid contacting zonemaintained under conditions sufficient to dissolve at least a portion ofthe hydrogen in the liquid hydrocarbon. Produced is a hydrocarbon liquidcontaining'dissolved hydrogen which is passed to a high temperature,high pressure hydrocarbon conversion zone wherein the hydrocarbon isthen contactedwith additional amounts of hydrogen.

In further, more limited embodiments, the conditions utilized in the lowpressure, vapor-liquid contacting zone include a pressure of about 50psig to about 500 psig, and a temperature of about 300 F. to about 800F. Preferably, the temperature, pressure and contact time are correlatedto produce an essentially hydrogen saturated hydrocarbon. Thehydrocarbon conversion conditions are preferably in a temperature rangeof about 600 F. to about 950 F. and pressure in the range of about 1,000psig to about 3,500 psig with the additional hydrogen being supplied toprovide a total amount of hydrogen of about 500 SCF/BBL to about 50,000SCF/BBL. The process of this invention is particularly suited tohydrocracking a hydrocarbon stock such as a petroleum based stock havingat least 10 percent by volume boiling over 1,050 F. or a distillateboiling within the range of about 400 F. to about l,l00 F.

;Other objects, embodiments, and more detailed description of theforegoing objects and embodiments will be found in the following moredetailed description of the present invention.

DETAILED DESCRIPTION The process and improvement of the presentinvention is applicable where a normally liquid hydrocarbon ishydroprocessed at elevated temperatures and elevated pressures. As usedherein, hydroprocessing refers to any processing of a hydrocarbon orpetroleum fraction under elevated pressure involving a consumption ofhydrogen by the hydrocarbon or petroleum fraction. Further, the termselevated temperature," elevated pressure," relatively high pressure and"relatively high temperature as used herein connote pressures in excessof about 1,000 psig and particularly pressures of about 1,000 psig toabout 3,500 psig and temperatures in excess of about 600 F andparticularly temperatures of about 700 F. to about 950 F. Thus,hydrocracking involving a substantial reduction (i.e., 50 percent ormore) in the molecular size of the charge with hydrogen consumption inthe range of to 300 SCF/BBL, hydrotreating involving removal ofimpurities such as sulfur and nitrogen with little molecularrearrangement or size reduction, or hydrorefining involvinghydrotreating and a minor part (i.e., 10 percent or less) ofhydrocracking are all included within the generally broad scope of thepresent invention, with the invention particularly suited tohydrocracking operations.

I Hydrocarbons applicable within the scope of the present invention varywidely and include a relatively pure hydrocarbon species, a mixture ofhydrocarbons, a contaminant containing hydrocarbon or mixture ofhydrocarbons with those hydrocarbons possessing a high solubility forhydrogen being preferred. Tl-Ius, an isomerization reaction involvingalkyl-aromatic hydrocarbons such as the C aromatics or paraffinichydrocarbons such as the C -C alkanes are within the generally broad.scope. of the present invention. Further, the term liquid hydrocarbonrefers to a hydrocarbon which exists in the liquid phase at relativelyambient temperatures and pressures with the normally gaseoushydrocarbons being excluded.

As indicated, the present invention is particularly suited to ahydrocracking operation and applies to the hydrocracking of eitherpetroleum or coal based hydrocarbon stocks. Particularly preferred arepetroleum based stocks, whether of a distillate or residual character,such as a stock having at least 10 percent by volume boiling above l,050F. or a distillate boiling within the range of about 400 F. to about l,lF. Suitable hydrocarbon stocks depend on the product desired (i.e.,whether gasoline, jet fuel, heating oil, lube oils, etc.) and includeheavy vacuum gas oils, topped crude oils, middle distillates and thelike. Also included within the scope of the present invention are blackoils characterized as being a heavy carbonaceous material containingasphaltic materials, of which more than percent (by volume) boils abovel,050 F. and which have API gravity at 60 F. of less than 20, such asvacuum tower bottoms and other residuum stocks.

The essence of the present invention lies in absorbing at least aportion of the hydrogen necessary for effecting a hydroprocessingreaction in the hydrocarbon charge stock passed to the reaction. Byabsorbing the hydrogen in the hydrocarbon, the compression costs andcompressor capacity required are lowered since that hydrogen absorbed inthe liquid need not be separately compressed to the high pressure of thehydroprocessing reaction. The savings arise because it is less expensiveto bring the hydrogen to the hydroprocessing conversion conditions whenit is in solution than when in the gaseous phase, since the costsassociated with pumping a liquid to elevated pressures is appreciablyless than compressing a gas to the same pressure. This is particularlyimportant since the hydrogen typically utilized in hydroprocessingreactions is available at a relatively low pressure. For example, themost common source of hydrogen, a platinum catalyzed reformer, onlyproduces hydrogen in a 100 psig to 300 psig range. Thus, since thehydrocarbon is also available only at a low pressure, both thehydrocarbon and hydrogen must be separately raised to the pressure ofthe reaction.

This hydrogen absorption into the liquid hydrocarbon is effected bycontacting the hydrogen and hydrocarbon in a low pressure, vapor-liquidcontacting zone maintained under conditions sufficient to dissolve atleast a portion of the hydrogen in the liquid hydrocarbon to produce ahydrocarbon liquid containing dissolved hydrogen. This contacting may beperformed by any means known to those trained in the art, such as packedcolumns, bubble cap tray columns, sieve columns and the like with thehydrogen being contacted with the hydrocarbon in either a countercurrentor cocurrent manner. Likewise, the hydrogen may be simply admixed withthe hydrocarbon by mixing in a pipeline or sparging in a closed vesselsuch as the feed surge drum utilized in atypical high pressureoperation.

Suitable contacting zone conditions include a pressure of about 50 psigto about 500 psig and a temperature of about 300 F. to about 800 F.However, it is preferred to utilize temperature levels almost as high asthe conversion conditions of the hydroprocessing reaction but just belowthe incipient level of cracking of the particular hydrocarbon streambeing processed, since hydrogen exhibits the unusual property of beingmore soluble in most hydrocarbon liquids at high temperatures than atlow temperatures. Further, it is preferred to correlate the contactingtime, contact conditions and hydrogen to hydrocarbon ratios so as toinsure essentially complete saturation of the hydrocarbon and almostcomplete absorption of the hydrogen present. While excess amounts ofhydrogen not capable of absorption, because of thermodynamic equilibriumlimitations, are readily removed, the presence of considerable amountsof excess unremoved hydrogen may result in two-phase flow to the liquidpumps which can cause cavitation and other malfunctions.

in any event, the resulting hydrocarbon liquid containing dissolvedhydrogen is then passed to a high temperature, high pressure reaction orhydrocarbon conversion zone wherein the hydrocarbon is hydroprocessed bymethods known to the art and whose exact process function is notnecessarily critical to the practice of this invention.

In the conversion or reaction zone, the hydrogen containing hydrocarbonis contacted with an additional amount of hydrogen so as to effect theparticular conversion reaction involved. This additional amount ofhydrogen is required since it is usually impossible to dissolve all thehydrogen needed, for a particular process, in the hydrocarbon beingprocessed. However, the hydrogen dissolved in the hydrocarbon need notbe separately compressed and the costs associated with separatelycompressing the hydrogen now in solution to the hydrocarbon conversionconditions are eliminated, thus rendering a more efficient, economicalprocess.

The present invention is suited to a high pressure, high temperaturehydrocracking operation, particularly a catalytic hydrocrackingoperation for the conversion of petroleum distillates and crude oil typefeedstocks to lower boiling, saturated products.

The catalytic hydrocracking process step in the present invention may beeffected in any suitable manner known to those trained in the art, andmay comprise either a batch or a continuous type operation. Whenutilizing a continuous type operation, which is the preferred manner ofeffecting the hydrocarbon conversion step of the present invention, thecatalyst may be disposed as a fixed bed in a catalytic reaction zonemaintained under the desired hydrocracking operation conditions.Hydrocarbon feedstocks containing the dissolved hydrogen and theadditional amount of hydrogen necessary to effect the reaction areadmixed and continuously charged to the hydrocarbon conversion zone andare contacted with the catalyst in either an upward, downward or radialflow fashion. The hydrocarbon conversion operation may also be effectedin a moving bed type operation, an ebullating bed operation, or in ahydrocarbon-catalyst suspension type operation in which the catalyst andhydrocarbons are commingled and passed through the reaction zone as aslurry. The preferred method of operation is a fixed bed, downflowsystem.

The operating conditions to be imposed on the hydrocarbon conversionzone will be dependent to a great extent upon the characteristics of thetotal charge to be processed, the hydrocarbon conversion reaction to beeffected and the desired product quality and product quantity. Wheneffecting a hydrocracking operation the temperature within the reactionzone will be controlled by controlling the temperature of thehydrocarbon hydrogen feed mixture so as to maintain a temperature in therange of about 700 F. to about 950 F. Further, a pressure in the rangeof about 1,000 psig to about 3,500 psig will be imposed on the system.The hydrocarbon charge contacts the catalytic composite at a liquidhourly space velocity in the range of about 0.5 hr. to about hr. Thetotal hydrogen concentration in the reaction zone, which includes thehydrogen dissolved in the hydrocarbon in the initial low pressurevapor-liquid contacting zone and the additional amount of hydrocarboncommingled with the liquid hydrocarbon feedstock, will be in the rangeof about 500 to 50,000 SCF/BBL (standard cubic-feet per barrel).Preferred total hydrogen concentrations are in the range of about 2,000to about 10,000 SCF/BBL. lf the particular hydroprocessing reaction is ahydrotreating or hydrorefining reaction, the conditions utilized willusually be less severe than those utilized in a hydrocracking operation.

The preferred method of effecting a hydrocracking operation comprisesraising the liquid hydrocarbon charge containing dissolved hydrogen to atemperature just below the incipient level of cracking, and preferably atemperature within the range of about 700 F. to about 800 F. if thehydrocarbon is not at that temperature already. In a separate heater,.the hydrogen stream which supplies the additional hydrogen needed inthe hydrocracking reaction is heated toa temperature above that at whichthermocracking of hydrocarbons occurs. For example, the hydrogen will beseparately heated to a temperature within the range of about 900 F. toabout l,000 F. or higher. The thus separately heated streams are thenadmixed prior to introduction into the reaction chamber.

A particularly preferred technique comprises introducing the separatelyheated streams into a common mixer-header wherein sufficient turbulenceis generated to assure through contact and complete heat exchangebetween the two streams prior to introduction into the reaction chamber.

The exact'catalytic composite to be utilized in a catalytichydroprocessing reaction is, as in the case of the conversionconditions, a function of the particular reaction desired and feedstockutilized. Generally, however, these catalysts can be characterized ascomprising a metallic component having hydrogenation activity, whichcomponent is usually composited within a refractory inorganic oxidematerial of either synthetic or natural origin. When effecting ahydrocracking operation, it is preferred to utilize a refractoryinorganic oxide of acidic nature. It is preferred to utilize suchcatalysts where a metallic component is combined with a carrier materialbut it is within the scope of the present invention to includesituations where a metallic component is unsupported such as in thepreviously mentioned slurry operation;

Suitable metallic components having hydrogenation activity are thoseselected from Groups VIB and VIII of the Periodic Table of Elements.Thus, a catalytic composite may comprise one or more metallic componentsselected from the group consisting of chromium, molybdenum, tungsten(wolfram), iron, cobalt, nickel, ruthenium, rhodium, palladium, osmium,iridium and platinum. The concentration of the catalytically activemetallic component or components is primarily dependent upon theparticular metal involved, process utilization and characteristics ofthe hydrocarbon charge stock. The metallic components of Group VIB arepreferably present in amounts within the range of about 1 to about 50percent by weight, the iron group metals of Group VIII in an amountwithin the range of about 0.2 percent to about 10 percent by weight,whereas the platinum group metals are preferably present in an amountwithin the range of 0.1 to about 5 percent by weight, all of which arecalculated as if the components existed as the elemental metal.

Refractory inorganic oxide carrier materials may comprise alumina,silica, zirconia, magnesia, titania, boria, strontia, hafnia, etc; thecrystalline aluminosilicates such as mordenite, faujasite, etc., andmixtures of two or more of these materials including silica-alumina,silica-zirconia, alumina-mordenite, alumina-silica-faujasite, and thelike. The precise composition and method of manufacturing of the carriermaterial is not essential to the present invention. Preferred carriermaterials include faujasite and those containing at least a portion ofsilica and preferably, a composite of alumina and silica containing agreater proportion of alumina. Particularly preferred is a catalystcomprising about 2 to about 10 percent by weight, nickel on a faujasitebase.

DESCRIPTION OF THE ATTACHED DRAWING The process of the present inventioncan be most clearly described by reference to the attached drawingschematically illustrating a hydrocracking type operation. Of necessity,certain limitations must be present in a diagram of the type presentedand no intention is made thereby to limit the scope of this invention toparticular reactants, concentrations, weights, operating conditions,catalysts, etc. Miscellaneous appurtenances including some valves,pumps, compressors, separators, reboilers, etc., have been eliminated.Only those vessels and lines necessary for a complete and clearunderstanding of the process of the present invention are illustrated,with any obvious modification made by those possessing expertise in theart of hydroprocessing being included within the generally broad scopeof the present invention.

Referring now to the schematic diagram, a hydrocarbon feedstock such asvacuum tower bottoms having a normal boiling point of about 1030F. andan API gravity at 60 F. of about 13.3, enters the process via line 1 andis passed to heater 2. Within heater 2, the hydrocarbon feed is heatedto a temperature of about 300 F. to about 800 F. and is removedtherefrom via line 3 and passed to vapor-liquid contactor 4.

Vapor-liquid contactor 4 is a vapor-liquid contacting means of a designwell known to those trained in the art, and containing spaced bafflemeans 5 to insure adequate mixing and contact between the heatedhydrocarbon and hydrogen. Within contactor 4, the

heated hydrocarbon feed and hydrogen, entering via,

The thus produced hydrogen saturated hydrocarbon is removed fromcontactor 4 via line 8 and pumped, via pumping means 9 through line 10to hydrocracking reactor 15. The additional amount of hydrogen needed toeffect the hydrocracking reaction over that supplied by recycle issupplied by compressing hydrogen in line 7 via compression means 11 tothe pressure of reactor 15. This compressed hydrogen passes fromcompressor 11 via line 12 and is commingled in line 10 with the hydrogensaturated hydrocarbon from contactor 4. This mixture is passed via line10, commingled with heated recycle hydrogen, the source of which to bedescribed later, entering via line 13 and the thus produced two-phasehydrogen-hydrocarbon system is passed through line 14 to hydrocrackingreactor 15. This hydrocracking reactor contains a fixed bed ofhydrocracking catalysts through which the hydrocarbon feed and hydrogenare contacted in a downflow fashion. Reaction conditions within reactor15 include a pressure of about 1,000 psig to about 3,500 psig and atemperature of avout 700 F. to about 950 F. The total amount of hydrogenabsorbed by the hydrocarbon in contactor 4 and the additional amountentering via lines 12 and 13 is such as to provide a total hydrogenconcentration of about 500 SCF/BBL to about 50,000 SCF/BBL, andpreferably in a range of about 2,000 to about 10,000 SCF/BBL.

Removed from reactor 15 via line l6 is a reaction product effluent whichis passed to high pressure separator 17 which is maintained atapproximately the same pressure and temperature as utilized in reactor15. The vapor and liquid phases present in reactor 15 effluent areseparated in separator 17 and the liquid is removedtherefrom via line 18for further fractionation and product recovered by means well known tothose trained in the art. Removed as vapors from separator l7, via line20, is a recycle hydrogen stream which comprises the majority of thehydrogen not consumed in the hydrocracking reactor and vent gas stream19. This recycle hydrogen stream 20 is compressed to the pressure ofreactor 15 by compression means 21 and passed via line 22 to heater 23.Within heater 23, the hydrogen is heated to a temperature level so thatwhen this hydrogen is commingled with the hydrocarbon feedstock, theresulting two-phase mixture is at the desired inlet temperature toreactor 15. This heated hydrogen is removed from heater 23 via line 13and commingled with hydrocarbon feed in line 10 and passed to reactor 15via line 14 as previously described.

From this foregoing description, it is readily apparent to those trainedin the art that by absorbing a portion of the hydrogen needed in reactor15 in vapor-liquid contactor 4, lesser amounts of hydrogen need becompressed in compressor 11 thereby resulting in a more efficient hightemperature, high pressure hydroprocessing process than heretofore hasbeen obtainable in the art.

I claim as my invention:

1. A process for the conversion of a hydrocarbon liquid by reaction withhydrogen which comprises physically dissolving a substantial portion ofsaid hydrogen in said liquid at a temperature of about 300 F. to about800 F. and a pressure of about 50 to about 500 psig., commingling theremainder of said hydrogen with the resultant solution of h drogen inhydrocarbon liquid, and sub ecting the mix ure to conversion at apressure of aboutl ,000 psig to about 3,500 psig and a temperature ofabout 700 F. to about 950 F.

2. The process of claim 1 further characterized in that said liquid issaturated with hydrogen at the firstmentioned temperature and pressure.

3. The process of claim 1 further characterized in that said conversionis hydrocracking.

4. The process of claim 1 wherein said hydrocarbon is a petroleum basedstock having at least 10 percent by volume boiling above 1,050 F.

5. The process of claim 1 wherein said hydrocarbon liquid is adistillate boiling within the range of about 400 F. to about 1,100 F.

6. The process of claim 1 wherein said remainder of the hydrogen issupplied in an amount to provide a total of about 500 SCF/BBL to about50,000 SCF/BBL.

' 7. The process of claim 1 wherein said conversion is in contact with acatalyst comprising at least one metallic component selected from themetals of Group VIB and Vlll of the Periodic Table combined with anacidic refractory inorganic oxide support.

1. A process for the conversion of a hydrocarbon liquid by reaction withhydrogen which comprises physically dissolving a substantial portion ofsaid hydrogen in said liquid at a temperature of about 300* F. to about800* F. and a pressure of about 50 to about 500 psig., commingling theremainder of said hydrogen with the resultant solution of hydrogen inhydrocarbon liquid, and subjecting the mixture to conversion at apressure of about 1,000 psig to about 3,500 psig and a temperature ofabout 700* F. to about 950* F.
 2. The process of claim 1 furthercharacterized in that said liquid is saturated with hydrogen at thefirst-mentioned temperature and pressure.
 3. The process of claim 1further characterized in that said conversion is hydrocracking.
 4. Theprocess of claim 1 wherein said hydrocarbon is a petroleum based stockhaving at least 10 percent by volume boiling above 1,050* F.
 5. Theprocess of claim 1 wherein said hydrocarbon liquid is a distillateboiling within the range of about 400* F. to about 1, 100* F.
 6. Theprocess of claim 1 wherein said remainder of the hydrogen is supplied inan amount to provide a total of about 500 SCF/BBL to about 50,000SCF/BBL.
 7. The process of claim 1 wherein said conversion is in contactwith a catalyst comprising at least one metallic component selected fromthe metals of Group VIB and VIII of the Periodic Table combined with anacidic refractory inorganic oxide support.